Problem with LCD backlight remaining on during ACPI sleep

2011-01-14T17:47:49Z

Runbei: Add solution for X32 and OpenSuse 11.3

==Problem description==
On some models the LCD backlight remains on during ACPI sleep.

==Affected Models==
*ThinkPad {{390X}} with kernel boot option ACPI=force
*ThinkPad {{A30}}
*ThinkPad {{A31p}}
*ThinkPad {{T30}}
*ThinkPad {{X31}},{{X32}}
*ThinkPad {{R51}}
(according to the relevant bug on the Kernel bug tracker ([http://bugzilla.kernel.org/show_bug.cgi?id=2576 bug 2576]))

==Partial solution==
If the ThinkPad has a radeon video chip, then switching off the light with the command
radeontool light off
will work, but only in a text-mode virtual terminal. If X is running, the light apparently comes back on when the kernel switches to text mode prior to sleeping. The solution in that case it to switch to a text mode console first.

logger "Software suspend to ram."
FGCONSOLE=`fgconsole`
chvt 1
radeontool light off
echo -n 3 >/proc/acpi/sleep
logger "Woke up from suspend."
radeontool light on
chvt $FGCONSOLE

Improvements are clearly possible. :-)

On the X32, at least, the bios will switch off the screen by default on a lid close, and suspending to ram interrupts this, and the screen will turn back on. This can be fixed by simply adding "sleep 5" before "echo -n 3 > /proc/acpi/sleep". The suspend will take longer, but the screen will remain off.

A similar script can be found on the [[How to configure acpid|acpid configuration HOWTO]] page.

{{NOTE|In Debian Testing (and maybe other Distributions/Debian versions using the hibernate-tool) you can simply uncomment the "RadeonTool yes" line in /etc/hibernate/ram.conf}}

==Using Powersaved==

If you use powersaved you can just edit the two scripts prepare_suspend_to_ram and restore_after_suspend_to_ram which are stored in /usr/lib/powersave/scripts/

add two lines to prepare_suspend_to_ram nearly at the end of the script:

# insert the next two lines:
chvt 1
radeontool light off
# this changes to a console nr. 1 and switches the light off

progress_finish
$SCRIPT_RETURN $EV_ID 0 "prepare_sleep finished successfully for $1"
EXIT 0

and to restore_after_suspend_to_ram
# insert the next two lines:
radeontool light on
chvt 7
# this switching the light on and changes to display #7 (where the x-server runs) -
#you can change it to another display if you want...
#(the way doing this with a variable like in the script above doesn't work, because it can't be stored between
#the two different scripts.

# $SCRIPT_RETURN is called in restore_after_sleep.
EXIT 0

Than you can suspend to ram with /usr/bin/powersave -u or just configure powersaved in a way that it suspends to ram when your notebook is closed. (As a frontend kpowersave is recomended).

==Using s2ram==

Just using the s2ram command from the uswsusp (Userspace Suspend) package should do the trick by appending the "-r" option (-r, --radeontool: turn off the backlight on radeons before suspending.).

==Editing menu.lst in OpenSuse==

A simple change in a start-up file in OpenSuse 11.3 corrected this problem

1. Open a terminal and type gnomesu gedit /etc/grub/menu.lst. When prompted, type root password and click OK.

2. Gedit opens with the menu.lst file displayed. Down the page a bit, there are several sections that begin with "###Don't change this comment"

3. The first section gives details for the default boot operating system. Somewhere in this long spec, find "vga=0x314" or vga=(something specific to your system).

4. Just before or after this vga spec, type "nomodeset" separated from the vga spec by a space.

5. Save the file and reboot. In OpenSuse, suspend/resume now works normally.

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Problem with LCD backlight remaining on during ACPI sleep